Processes for the preparation of liquid developers with low vapor pressure components

Abstract

A process for the preparation of liquid developer compositions which comprises mixing a resin with a low vapor pressure oil at elevated temperatures permitting the resin to melt and enabling the formation of a resin oil mixture; thereafter adding to the oil resin mixture at elevated temperatures pigment particles, and stirring until the pigment has become dispersed in the resin; followed by attriting the mixture while cooling, for example, to ambient temperatures; thereafter filtering the aforementioned mixture, and dispersing the product in a low viscosity oil; and subsequently adding to the formed mixture a charge control additive.

What is claimed is: 
     
       1. A process for the preparation of liquid developer compositions which comprises admixing molten resin components in a vehicle component possessing a vapor pressure of from about 0.01 to about 0.1 millimeter of mercury; thereafter adding thereto pigment particles; subsequently cooling and attriting the aforementioned resulting mixture thereby enabling entrapment of the vehicle in the developer composition; thereafter filtering and dispersing the resulting particles in a low viscosity oil; and adding to the formed composition a charge control director component. 
     
     
       2. A process for the preparation of liquid developer compositions which comprises mixing a resin with a low vapor pressure oil at elevated temperatures permitting the resin to melt and enabling the formation of a resin oil mixture; thereafter adding to the oil resin mixture at elevated temperatures pigment particles, and stirring until the pigment has become dispersed in the resin; cooling the mixture with attrition, thereby enabling entrapment of said oil in the developer composition; thereafter filtering the aforementioned mixture, and dispersing the product in a low viscosity oil; and subsequently adding to the formed mixture a charge control additive. 
     
     
       3. A process in accordance with claim 2 wherein the mixing is accomplished at a temperature of from about 90° to about 110° C. 
     
     
       4. A process in accordance with claim 2 wherein the low vapor pressure oil is present in the mixture in an amount of from about 80 percent by weight to about 90 percent by weight. 
     
     
       5. A process in accordance with claim 2 wherein the vapor pressure of the oil selected is from about 0.01 to about 0.1 millimeter of mercury. 
     
     
       6. A process in accordace with claim 2 wherein the low vapor pressure oil is selected from the group consisting of Isopar V and Magiesol 60. 
     
     
       7. A process in accordance with claim 2 wherein the pigment particles are selected from the group consisting of carbon black, cyan, magenta, yellow, or mixtures thereof. 
     
     
       8. A process in accordance with claim 7 wherein the pigment is present in an amount of from about 3 percent by weight to about 25 percent by weight. 
     
     
       9. A process in accordance with claim 2 wherein subsequent to dispersion of the pigment in the resin particles the mixture is allowed to cool to room temperature over a period of from about 3 to about 5 hours enabling particles with an average diameter of from about 2 to about 3 microns. 
     
     
       10. A process in accordance with claim 2 wherein the charge director is present in an amount of from about 0.01 to about 2 percent by weight. 
     
     
       11. A process in accordance with claim 2 wherein the charge director is selected from the group consisting of polyisobutylene succinimide and lecithin. 
     
     
       12. A process in accordance with claim 2 wherein the developers possess an image transfer efficiency of from about 80 percent to about 99.8 percent. 
     
     
       13. A process in accordance with claim 2 wherein the charge control additive is present in an amount of from about 0.02 percent by weight to about 0.05 percent by weight. 
     
     
       14. A process in accordance with claim 2 wherein the charge director is selected from a group consisting of salts of cadmium, calcium, manganese, magnesium, and zinc salts of heptanoic acid. 
     
     
       15. A process in accordance with claim 2 wherein the charge director is selected from barium, aluminum, cobalt, manganese, zinc, cerium and zirconium salts of 2-ethyl hexanoic acid. 
     
     
       16. A process in accordance with claim 1 wherein the charge director is selected from the group consisting of the barium, aluminum, zinc, copper, lead and iron salts of stearic acid. 
     
     
       17. A process in accordance with claim 1 wherein the charge director is selected from the group consisting of polyisobutylene succinimide and lecithin. 
     
     
       18. A process in accordace with claim 1 wherein the low viscosity oil is Isopar G or Isopar L. 
     
     
       19. A process in accordance with claim 2 wherein the low viscosity oil is Isopar G or Isopar L.